That’s really bizarre. Our expected points model says 1st-and-10 at the 20 is worth about 0.3 EP, and 1st-and-10 at the 40 is worth 1.6 EP (a difference of 1.3). Now, that’s in net points, but Keith Goldner’s Markov rest-of-drive model says the offense’s exp pts go from about 1.4 to 2.1, a difference of 0.7 (I attribute the difference between that and our EP to a simultaneous decrease in the defense’s expected pts when they get the ball back). At any rate, that’s nowhere near 3 points. I have no clue how he came up with that.

could it be that making it to the 40 proxies some unobserved determinants of getting a field goal for which you have failed to account in your calculation of expected points? 1st and ten at the 40 is not the same as 1st and ten at the 40 given a you just returned a kickoff to the 40.

In short, no. All that gets factored into the play-by-play data. The most likely cause of an error like this someone getting the opponent’s 40 and his own 40 mixed up. The 40 yard difference from your own 20 and the opponent’s 40 yard line is worth about 3 points.